1. Field of the Invention
The present invention relates generally to the field of ball valves, and more particularly, to a ball valve configured with flow, no flow and life-sustaining flow operating positions.
2. Background of the Invention
Ball valves are well known and generally include a valve body defining a valve chamber, a substantially spherical ball member rotatably positioned within the valve chamber, and annular seats for sealing engagement with the ball positioned adjacent inlet and outlet openings of the valve chamber. The ball member further defines an internal passage therethrough that is rotated in the direction of axial alignment with the valve body to open the valve to form a flow path from the valve inlet to the valve outlet, and rotated in the direction perpendicular to the valve body to close the valve to block the flow of fluid through the valve body. Rotation of the ball member may be achieved using a lever for selectively rotating the ball member between the open and closed positions.
The annular seats are axially constrained by sealing engagement with the surface of the valve member such that fluid is prevented from flowing between the ball member and internal walls of the valve chamber. The rate of flow through the internal passage is controlled by adjusting the degree of axial alignment of the internal passage with the flow path of the valve body.
While conventional ball valves exist configured to provide two operating positioned, i.e., flow and no flow operating positions, what is needed is a ball valve configured to provide a third operating position in which the valve can be closed yet maintain life-sustaining flow at all times.